I have not seen any reports of this nor do we have any changes in the last day, so it probably is that your code is using the same token to do stats calls for more than one account and/or running service. Sharing cost limit for multiple accounts has always been the #1 reason for rate limit issues on v0 endpoints.

Officially we are getting close to the end of life for v0 stats so I would encourage you to already start moving over to v1 ASAP.

Cost limiting was how v0 stats are rate limited, you are given a specific amount of ‘cost’ to retrieve stats for a period of 15 minutes and after you use it, you must wait 15 minutes for the next window to open up. You should inspect the headers to see cost remaining go down after each stats query you do (the more data you request at once, the more cost you will use), and generally follow our best practices: https://dev.twitter.com/ads/analytics/best-practices

Your application may not be able to sync all of the stats for an account within a single rate limit window, and may need to run for up to several hours when syncing a lot of data (while waiting for the next windows to open up). A lot of this is simplified with the async job syncing of v1.